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Author Topic: Meta-chert Pendant  (Read 246 times)

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lithicbeads

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Meta-chert Pendant
« on: December 27, 2018, 07:19:50 PM »

Meta - chert pendant from Washington.  The huge array of meta - cherts from Washington have one commonality , they are difficult to work because they have a much lower silica content than jaspers and agates. The siliceous meta - cherts have a range of silica content from 89% to 92 % while agates and jaspers that we see in the trade are 99 % silica and are very easy to work. These meta - cherts have been closely studied by geologists and it is known that they form where the Pacific plate meets subsidiary plates causing spreading centers , places where magma surfaces and widens the earth's crust. Associated with these spreading centers are black smokers which are mineral laden jets of hot water bringing iron and manganese up to the ocean bottom where it precipitates out of solution and mixes with silica that is of biological origin .The silica is the remainder of diatom shells falling our of the water column minus the carbonate content which goes into solution at these depths. A couple of metamorphisms and you have meta- chert. The pink is a conglomeration of tiny maganese garnets, spessartite garnets. It actually works like glass.47 mm long , 6 mm hole.
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rocks2dust

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Re: Meta-chert Pendant
« Reply #1 on: December 27, 2018, 07:27:52 PM »

That's super-attractive: both the stone and what you've done with it :icon_thumleft:
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r2d

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hummingbirdstones

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Re: Meta-chert Pendant
« Reply #2 on: December 28, 2018, 05:53:41 AM »

Agree with r2d.  Very pretty with a pleasing pattern and colors.
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Robin

vitzitziltecpatl

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Re: Meta-chert Pendant
« Reply #3 on: December 28, 2018, 06:02:50 AM »

Thanks for kick-starting my brain this morning, Frank, with a very nice pendant. How consistent are the hardnesses of the different colors? I really like the color and pattern in that stone.

lithicbeads

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Re: Meta-chert Pendant
« Reply #4 on: December 28, 2018, 07:50:12 AM »

Excellent question. The hardnesses vary a lot. The silica was not crystalline or microcrystalline but rather amorphous like glass.When the rock was metamorphosed it was crystallized but it was also down metamorphosed and lost some of it's crystalline nature. The pink garnet is the hardest.
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vitzitziltecpatl

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Re: Meta-chert Pendant
« Reply #5 on: December 28, 2018, 08:02:38 PM »

Well you sure got a nice looking pendant out of material that's - as you said - difficult to work. Not many things we deal with more frustrating than having amazing colors and patterns that won't polish consistently from one to the other.

We got some Owyhee Green "Jasper" from Tony that has similar colors in some of it. Also very inconsistent but worth the extra effort when it has interesting patterns.

Thanks for the show and tell on a very interesting type of stone.
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